I've seen several posts now on the forums where WPMU users are using/recommending W3 Total Cache for their WPMU installs over plugins like WP-Super-Cache in "half on" mode, for example.
NOTE: My WPMU install is still pretty small (<100 blogs, but growing), and we're hosted on one of the pSek WPMU plans. And we've got multi-DB installed and working (16 DBs).
NOTE 2: We cannot use memcached or nginx while we're on pSek shared hosting.
Now, I'm trying to implement site-wide caching and a CDN (Amazon CloudFront w/ S3), but I've just learned that W3TC and Multi-DB don't work together, since they each require a 'db.php' file in /wp-content/
Has anyone gotten these two to work together? Any recommendations?